PROJECT SUMMARY The 1980s heralded the advent of fetal surgery, bringing forth a new paradigm of treatment for fetuses with significant congenital defects including spina bifida, congenital diaphragmatic hernia, and complications such as twin-twin transfusion syndrome. Earlier treatment in the womb allows for natural and continued development within the safety of the uterus, improving outcomes for these individuals even before they are born. Clinical studies demonstrated that prenatal spina bifida treatment improved outcomes as compared to postnatal surgery by reducing the incidence or severity of potentially devastating neurologic effects. However, these procedures and many other fetal interventions have been plagued by an ?Achilles heel? known as preterm premature rupture of membranes (PPROM). In order to realize the full promise of fetal intervention and lower the risks associated with fetal procedures, the problem of PPROM must be mitigated. Current research has focused on further refinement of surgical techniques that diminish the risks or incidences of PPROM due to medical interventions. There have been a myriad of potential solutions to treat PPROM after the rupture has occurred, yet none of them have been shown to be clinically effective. Specifically, research has concentrated on repairing ruptures by using certain adhesives or tissue sealants. Despite the plethora of approaches, nothing has been able to reliably lower the occurrence of PPROM across procedures, and there exists no prophylactic standard of care, only management after PPROM has occurred. A new technique and unique approach that consists of presealing the chorioamniotic membrane prior to membrane disruption has recently been demonstrated. In this proposed work we aim to demonstrate a high-resolution, ultrasonic micro-transducer that can accurately locate the thin chorioamniotic membrane, thereby making the presealing approach clinically viable. For the Phase I project we propose the following Specific Aims to show feasibility: (1) Demonstrate a high- resolution, ultrasonic micro-transducer that fits in a high-gauge needle; (2) Demonstrate precision guidance of sealant dispensing using an ultrasound micro-transducer.